1. Field of the Invention
The Invention relates to a hollow molded part in the shape of an A-column for a motor vehicle made of a metallic material produced by inner high pressure metal forming out of a mold blank and to a method of production of the hollow molded part, wherein the hollow molded part exhibits a closed cross-section and a reinforcement according to the preamble of the patent claims.
2. Brief Description of the Background of the Invention Including Prior Art
A vehicle structural member or, respectively, a hollow molded part with closed cross-section is known from the German printed Patent document DE 19518946 A1, wherein the vehicle structural member or, respectively, the hollow molded part is formed with at least two component parts connected to each other. The term closed cross-section is associated with the circumference of the hollow mold part closed in itself. This hollow molded part represents a front column or, respectively, an A-column of a motor vehicle body and is formed out of an outer plate, a column stiffening and an inner column made of light metal. The reinforcement element is here disposed within the region of the closed cross-section of the vehicle structural member. It is furnished to attach several individual elements, such as for example pipes, plates, or the like along the hollow reinforcement element for further increasing the strength.
A solution is described in the German printed Patent document DE 10126183 A1, wherein a stiffening element is disposed in the inner chamber of the hollow molded part, wherein the stiffening element is connected to the hollow molded part and wherein the stiffening element extends through a recess of the hollow molded part into the inner space of the hollow molded part. The frame structure of a vehicle is described in the German printed Patent document DE 20 20 6524 U1, wherein a tubular frame part is furnished and wherein a sheet metal component part is furnished at the outer circumference of the tubular frame part for reinforcement of the frame structure. The disadvantage of this solution comprises the multipart construction and the therewith associated high production expenditure.
The body of a motor vehicle is described in the German printed Patent document DE 4106501 A1, wherein a part of the supporting structure of the body is composed out of two extruder profiles open relative to each other, and wherein the extruder profiles exhibit a closed cross-section after a connection to each other. The extruder profiles are here weight optimized based on shape and wall thickness corresponding to the expected requirements as to stiffness. The multiple part construction of the respective frame part is here also disadvantageous.
The U.S. Pat. No. 6,553,243 B1 to Bignucolo et al. describes a method for the production of a front axle of a motor vehicle. A first pre-form with the center cylindrical region 3 is here produced out of a section by a radial forming method, wherein the center cylindrical region 3 exhibits two cylindrical ends 4, wherein the diameter of the two cylindrical ends 4 is smaller than the diameter of the center region 3. A frustro-conical shaped region 5 extends between the center cylindrical region 3 and each cylindrical end region 4. A second pre-form is produced by having the first pre-form pressed or upset in a press such that an elliptical cross-section 6b is generated in the center region 3, wherein a recess 6b is present at the two ends of the elliptical cross-section 6b. Then according to a further pre-form step, a square cross-section 7a is formed in the center region.
Finally the production of the front axle occurs by inner high-pressure forming. This method requires overall four forming stages in order to form the front axle. The production of an A-column of a motor vehicle is not possible with the method according to Bignucolo et al., since a relatively strong bending is present in connection with the A-column and since Bignucolo et al. do not furnish a bending method.
A solution is described U.S. Pat. No. 5,823,031, by way of which method an expanding and bending of a tube becomes possible. The bent region joins at the expanded region. A wall thickness increase is not possible with the solution of U.S. Pat. No. 5,823,031. Also according to U.S. Pat. No. 5,823,031 the bending of the tube is not performed under the action of an axial pull tension. The production of an A-column of a motor vehicle with the reinforcement region is not possible with the solution of U.S. Pat. No. 5,823,031.
It is an object of the present Invention to furnish a method for the production of a hollow form part.